Abrasive for the production of a grinding tool, grinding tool and method for operating a grinding tool of this type

ABSTRACT

A grinding tool (1) has a replaceable abrasive (4). A grinding layer (9) of the abrasive (4) faces a drive shaft (2) of the grinding tool (1). This enables a grinding of a workpiece (W) while exerting a tensile force (F). Surface areas (O) of the workpiece (W) facing away from a processor may thus be processed easily and flexibly.

The invention relates to an abrasive for the production of a grinding tool. The invention further relates to a grinding tool comprising an abrasive as well as a method for operating a grinding tool of this type.

From DE 198 59 118 A1 (corresponds to U.S. Pat. No. 5,938,514 A), a grinding tool is known in which an abrasive disk is attached to a connecting piece. The connecting piece comprises a disk and clamping means between which the abrasive disk is clamped. The connecting piece is attached to a backing plate by means of a locking-nut, such that the abrasive disk is supported by the backing plate. The locking-nut is connected to a shaft so that the abrasive disk can be driven in rotation by means of the shaft.

It is an object of the invention to create an abrasive for the production of a grinding tool which can be used simply and flexibly for grinding a workpiece.

This object is achieved by an abrasive having the features of claim 1. According to the invention, it has been recognized that the range of use of the abrasive is increased in a simple manner if the grinding layer and the connecting element are arranged on a common side of the abrasive. As a result, processing or grinding a workpiece while exerting a tensile force is possible. In particular, surface areas of a workpiece which are difficult to access and which face away from a processor can be processed in a simple and flexible manner. By means of the connecting element, the abrasive can be connected in a simple manner to the abrasive holder and is thus a replaceable component of the grinding tool. As a result of the fact that the abrasive can be exchanged in a simple manner, a plurality of different processing steps can be performed on the surface regions facing away from the processor, using different abrasives according to the invention. For example, material can first be removed from the surface regions. Subsequently, the surface regions can be smoothed. The abrasive preferably has a diameter D, wherein. 10 mm≤D≤230 mm, in particular 35 mm≤D≤135 mm. The abrasive is in particular designed as an abrasive disk and/or as an abrasive wheel.

The connecting element is used for the friction-fit and/or form-fit connection to the abrasive holder. Preferably, the abrasive holder has a counter-connecting element. The connecting element is arranged concentrically to an axis of rotation of the abrasive or the grinding layer. In particular, the connecting element is of the counter-connecting type. This means that the connecting element is not exclusively formed as an opening in the grinding layer or the abrasive.

The abrasive comprises, for example, an abrasive body made of abrasive grains bonded with synthetic resin. As a result, the entire surface of the abrasive body can be used for grinding. In particular, the abrasive body forms a first grinding layer facing the abrasive holder and a second grinding layer facing away from the abrasive holder. The connecting element is attached to the abrasive body concentrically to the axis of rotation of the abrasive. In particular, the abrasive serves for roughing grinding a workpiece.

For example, the abrasive includes a supporting body to which the grinding layer is attached.

An abrasive according to claim 2 ensures easy and flexible grinding of a workpiece. The supporting body is preferably designed to be rigid and/or elastically deformable. In particular, the supporting body comprises an attachment region and a working region surrounding the attachment region, which are arranged concentrically with respect to an axis of rotation of the abrasive and/or the supporting body. The supporting body is designed to be preferably rigid in the attachment region and/or designed to be preferably rigid and/or elastically deformable in the working region. For example, the supporting body comprises an inner working region and an outer working region, wherein the outer working region surrounds the inner working region such that the inner working region is arranged between the attachment region and the outer working region. For example, the inner working region and/or the outer working region are formed to be rigid and/or elastically deformable. For example, the inner working region is designed to be rigid and the outer working region is designed to be elastically deformable so that surface areas of a workpiece with curvature facing away from a processor can be processed with the grinding layer arranged in the working region. The connecting element is attached to the supporting body, in particular concentrically with respect to the axis of rotation of the abrasive.

The supporting body comprises at least one material selected from the group consisting of glass fibers, carbon fibers, cotton, polyester, vulcanized fiber, wood, plastic material and/or metal. Preferably, the supporting body comprises at least one fiber layer. The supporting body in particular serves to reinforce and/or stiffen the grinding layer. The connecting element is in particular connected to the supporting body in a form-fit and/or material-fit manner.

The supporting body preferably comprises at least one fiber layer comprising a woven fabric and/or a scrim and/or a nonwoven fabric and/or vulcanized fiber. Preferably, the at least one fiber layer is embedded in a binding agent. Preferably, the at least one fiber layer is partially movably arranged in the binding agent. As a result, a free relative movement is possible within the at least one fiber layer, so that the supporting body achieves a high vibration and noise damping. In order to achieve the free relative movement, within the at least one fiber layer, on the one hand so much binding agent is used that the supporting body has sufficient stability and, on the other hand, so little binding agent is used that the at least one fiber layer does not have a continuous and/or full-surface bond with the binding agent. Preferably, the binding agent is a resin and/or a plastic material. Preferably, the binding agent is a thermoset, in particular phenolic resin or epoxy resin.

An abrasive according to claim 3 ensures an easy and flexible grinding of a workpiece. The grinding layer comprises abrasive grains applied directly to the supporting body so that the supporting body forms a backing. In particular, the abrasive grains are applied electrostatically. The abrasive grains, which are introduced into an electrostatic field, move along the field lines in the direction of the adhesive and, when in contact with the adhesive, adhere to the supporting body so that the abrasive grains form the grinding layer. In particular, the grinding layer is formed in three dimensions. For this purpose, the grinding layer is preferably configured as to be curved relative to an axis of rotation of the abrasive in the radial direction and/or in the circumferential direction about the axis of rotation. The abrasive—viewed from the side of the connecting element or the abrasive holder—is curved in the radial direction, in particular concavely. The adhesive is at least one material selected from the group of thermosets, elastomers, thermoplastics and synthetic resins. Preferably, the adhesive is a thermoset, in particular a phenolic resin or an epoxy resin. The phenolic resin is, for example, a resol and/or a novolak.

An abrasive according to claim 4 ensures an easy and flexible grinding of a workpiece. The grinding layer is preferably configured as to be curved in a radial direction relative to an axis of rotation of the abrasive and/or in a circumferential direction about the axis of rotation. The grinding layer is formed three-dimensionally by the curvature. Due to the curved design, the abrasive has a pin-like and/or pot-like shape. The grinding layer thus comprises a first abrasive region, which enables grinding while exerting a tensile force, and a second lateral abrasive region, which extends the range of use of the abrasive. The first abrasive region is in particular configured to be planar in shape.

An abrasive according to claim 5 ensures an easy and flexible grinding of a workpiece. The first grinding layer serves for grinding while applying a tensile force, whereas the second grinding layer is opposite to the first grinding layer and serves for grinding while applying a compressive force. The supporting body is disposed between the first grinding layer and the second grinding layer. The first grinding layer can process surface areas of the workpiece facing away from a processor, whereas the second grinding layer can process surface areas of the workpiece facing toward the processor. The first grinding layer and the second grinding layer may be identical or different in structure and/or shape.

An abrasive according to claim 6 ensures an easy and flexible grinding of a workpiece. The abrasive grains used make the abrasive easily and flexibly adaptable to the processing requirements. The abrasive grains have a geometrically definite shape and/or a geometrically indefinite shape. The abrasive grains comprise at least one material selected from the group consisting of ceramics, corundum, in particular zirconium corundum, diamond, cubic crystalline boron nitride (CBN), silicon carbide and tungsten carbide. The abrasive grains may be applied to a supporting body in a single layer or in multiple layers. When a plurality of superimposed grinding layers are formed, an adhesive is applied to the respective underlying grinding layer and the subsequent grinding layer is applied. In particular, the grinding layer comprises a base bond, abrasive grains and a top bond. The abrasive grains may be bonded by means of a synthetic resin so that the abrasive grains together with the synthetic resin form an abrasive body.

An abrasive according to claim 7 ensures an easy and flexible grinding of a workpiece. By means of the rotary connecting element, the abrasive can be interchangeably connected to the abrasive holder in a simple and flexible manner. In particular, the rotary connecting element is selected from the group consisting of a threaded pin, a threaded bore, a bayonet locking component and a snap-in locking component. The rotary connecting element is reversibly connectable to a rotary counter-connecting element of the abrasive holder. The rotary connecting element is connectable to a rotary counter-connecting element by rotation about an axis of rotation relative thereto, and is disconnectable again by rotation in an opposite direction. The rotary connecting element can be connected in a form-fit manner and/or friction-fit manner to the abrasive holder or a rotary counter-connecting element by rotation about an axis of rotation.

It is one further object of the invention to create a grinding tool which can be used easily and flexibly for grinding a workpiece.

This object is achieved by a grinding tool with the features of claim 8. Due to the fact that the grinding layer faces the drive shaft, surface areas of a workpiece facing away from a processor can be machined while exerting a tensile force. The abrasive is interchangeably attached to the abrasive holder so that different abrasives may be used for a plurality of different processing steps. For example, the abrasive comprises abrasive grains bonded with synthetic resin such that the abrasive grains bonded with synthetic resin form an abrasive body. The abrasive comprises, for example, a supporting body on which the grinding layer is arranged. In particular, the abrasive is formed as an abrasive disk and/or an abrasive wheel. The abrasive comprises, for example, a flexible backing or a flexible supporting body on which the abrasive grains are arranged. The abrasive is preferably spanned on, clamped, glued and/or reversibly attached to the abrasive holder by means of a connecting element. The grinding tool is rotatably drivable by means of a tool drive. The grinding tool is manually guidable. The abrasive has a diameter D, wherein: 10 mm≤D≤230 mm, in particular 35 mm≤D≤135 mm. The abrasive may in particular also be further configured according to at least one of claims 1 to 7.

A grinding tool according to claim 9 ensures an easy and flexible grinding of a workpiece. The connecting element allows the abrasive to be connected to the abrasive holder in a simple and flexible manner in an exchangeable manner. Preferably, the connecting element is formed as a rotary connecting element.

A grinding tool according to claim 10 ensures an easy and flexible grinding of a workpiece. By means of the counter-connecting element, the abrasive holder can be connected to the connecting element of the abrasive in a simple and flexible manner. This enables the abrasive to be replaced easily and quickly. Preferably, the counter-connecting element is designed as a rotary counter-connecting element.

A grinding tool according to claim 11 ensures an easy and flexible grinding of a workpiece. The supporting body is preferably designed to be rigid and/or elastically deformable. The connecting element is preferably connected to the supporting body in a form-fit and/or material-fit manner. The grinding layer is directly attached to the supporting body, in particular by means of an adhesive. Furthermore, the supporting body is designed to be flexible, for example, and forms a backing to which abrasive grains are attached by means of an adhesive.

A grinding tool according to claim 12 ensures an easy and flexible grinding of a workpiece. Due to the fact that at least one holder component of the abrasive holder is arranged on a side of the abrasive facing away from the drive shaft, the abrasive holder supports the abrasive while exerting a tensile force during grinding. The abrasive is thus arranged in the direction of an axis of rotation between the abrasive holder or a holder component and the drive shaft. This arrangement provides additional support for the abrasive when the inherent stability of the abrasive is insufficient. The holder component can be designed to be rigid and/or elastically deformable for support.

A grinding tool according to claim 13 ensures an easy and flexible grinding of a workpiece. Due to the fact that the abrasive is arranged between the two holder components, the abrasive may be supported and/or fixed by means of the holder components. The first holder component is reversibly connectable to the second holder component, i.e. connectable and disconnectable again. For this purpose, the holder components form a threaded connection, for example.

The first holder component is arranged on the side facing the drive shaft. The first holder component is connected to the drive shaft. The first holder component and the drive shaft are connected, for example, by means of a threaded connection or are integrally formed with one other. The first holder component has a diameter D₁ and the abrasive has a D, wherein D₁<D, in particular D₁≤0.5·D, in particular D₁≤0.3·D. As a result, the first holder component substantially does not interfere with the abrasive, i.e. the working region that can be used for grinding.

The second holder component is arranged on a side of the abrasive facing away from the drive shaft and supports the abrasive in particular in addition to the inherent stability of the abrasive. The second holder component has a diameter D₂. For example, the following applies: D₂≥D, so that the abrasive is supported all over by the second holder component. Alternatively, for example, the following applies: D₂≤D, such that the abrasive is held and possibly also supported by the second holder component.

It is further an object of the invention to create a method for operating a grinding tool which enables an easy and flexible grinding of a workpiece. The advantages of the method according to the invention correspond to the advantages of the grinding tool according to the invention and the abrasive according to the invention, which have already been described. By grinding the workpiece while exerting a tensile force acting in the direction of a processor or to be exerted by a processor, surface areas of the workpiece facing away from the processor can be processed easily and flexibly. The method according to the invention thus enables the processing of surface areas of a workpiece which are difficult to access.

Further features, advantages and details of the invention will be apparent from the following description of several embodiments. In the drawings:

FIG. 1 shows an axial section through a grinding tool with an abrasive holder and an abrasive replaceably attached thereto, according to a first embodiment,

FIG. 2 shows a top view onto the abrasive in FIG. 1 ,

FIG. 3 shows an axial section through a grinding tool with an abrasive holder and an abrasive replaceably attached thereto, according to a second embodiment,

FIG. 4 shows an axial section through a grinding tool with an abrasive holder and an abrasive replaceably attached thereto, according to a third embodiment, and

FIG. 5 shows an axial section through a grinding tool with a two-part abrasive holder and an abrasive replaceably attached thereto, according to a fourth embodiment.

In the following, a first embodiment of the invention is described with reference to FIGS. 1 and 2 . A grinding tool 1 comprises a drive shaft 2, an abrasive holder 3 and an abrasive 4. The drive shaft 2 defines an axis of rotation 5 for driving the grinding tool 1 in rotation by means of a hand-held tool drive not shown in more detail. The drive shaft 2 and the abrasive holder 3 are connected to each other by means of a common threaded connection 6. The abrasive holder 3 further comprises a counter-connecting element 7, which is described in more detail below in connection with the abrasive 4.

The abrasive 4 comprises a supporting body 8 on which a grinding layer 9 is arranged. The grinding layer 9 is arranged on a first side S₁ facing the abrasive holder 3 in a fixed state of the abrasive 4. Furthermore, the abrasive 4 has a second side S₂ facing away from the abrasive holder 3. The grinding layer 9 comprises abrasive grains 11 directly attached to the supporting body 8 by means of an adhesive 10. The grinding layer 9 additionally comprises a cover bond 12 applied to the abrasive grains 11.

The abrasive 4 is replaceably connected to the abrasive holder 3. The abrasive 4 comprises a connecting element 13, which is fixed to the supporting body 8 concentrically to the axis of rotation 5 of the grinding tool 1 or of the abrasive 4. The connecting element 13 is arranged on the first side S₁ of the supporting body 8 or of the abrasive 4 and faces the abrasive holder 3. The connecting element 13 is connected to the supporting body 8 in a material-fit and/or form-fit manner.

The connecting element 13 forms a circular attachment region B, which is arranged concentrically with regard to the axis of rotation 5. The attachment region B is surrounded by an annular inner working region A₁, which in turn is surrounded by an annular outer working region A₂. The inner working region A₁ and the outer working region A₂ are collectively referred to as the working region A. The abrasive 4 has a diameter D for which the following applies: 10 mm≤D≤230 mm, in particular 35 mm≤D≤135 mm.

The supporting body 8 and the grinding layer 9 arranged thereon are formed in three dimensions. In the inner working region A₁, the grinding layer 9 is formed to be planar. In contrast, in the outer working region A₂, the grinding layer 9 is formed to be curved in a radial direction R and in a circumferential direction U. When viewed from the first side S₁, the grinding layer 9 is concavely curved in the radial direction R. The supporting body 8 is formed to be rigid and/or elastically deformable.

The connecting element 13 is designed as a rotary connecting element. For this purpose, the connecting element 13 has a plurality of projections 14 which are arranged as to be rotationally symmetrical about the axis of rotation 5 and bound a receiving opening 15 in certain regions. The receiving opening 15 serves for inserting and receiving the counter-connecting element 7. The counter-connecting element 7 is formed as a rotary counter-connecting element and has a plurality of counter-projections 16 extending in the radial direction R. The counter-projections 16 can be inserted into the connecting element 13 in the region outside the projections 14 through the receiving opening 15 by a movement along the axis of rotation 5. By a subsequent rotation about the axis of rotation 5, the counter-projections 16 are clamped to the projections 14 in a form-fit and friction-fit manner.

The operating principle of the grinding tool 1 is as follows:

The grinding tool 1 serves for processing a surface area O of the workpiece W which is difficult to access and faces away from a processor of the workpiece W. The abrasive holder 3 is first connected to the drive shaft 2, which has a length suitable for processing the workpiece W. The drive shaft 2 is clamped in a manually guided tool drive, which is not shown in more detail. The abrasive 4 is connected to the counter-connecting element 7 of the abrasive holder 3 by means of the connecting element 13.

The abrasive 4 is now driven in rotation about the axis of rotation 5 by means of the tool drive. By exerting a tensile force F in the direction of the axis of rotation 5, the processor guides the grinding layer 9 to the surface area O facing away, such that the latter is processed or ground in the desired manner. Unwanted material projections M can be easily and flexibly removed in this way. Due to the fact that the grinding layer 9 is configured to be curved in the outer working region A₂, it is also possible to process fillet welds K of the workpiece W which are facing away.

The abrasive 4 is replaceable so that, for example, after a rough processing, a fine processing can be carried out in an easy and flexible manner. For this purpose, the abrasive 4 is detached from the abrasive holder 3 by means of the connecting element 13 and a new abrasive 4 is attached to the abrasive holder 3. The new abrasive 4 is configured in accordance with FIGS. 1 and 2 , but has a grinding layer 9 and abrasive grains 11 which are suitable for fine processing.

Hereinafter, with reference to FIG. 3 , a second embodiment of the invention is described. In contrast to the first embodiment, the supporting body 8 has a second grinding layer 17 on the second side S₂, which is substantially opposite the first grinding layer 9. The supporting body 8 is thus arranged between the first grinding layer 9 and the second grinding layer 17. The second grinding layer 17 is configured corresponding to the first grinding layer 9. By means of the second grinding layer 17, the workpiece W can be processed at a surface area O′ facing the processor. For this purpose, the processor guides the grinding tool 1 to the surface area O′ and processed it by exerting a compressive force F′ with the second grinding layer 17. The grinding tool 1 may thus also process or remove material projections M′ which face the processor. With regard to the further construction and the further operational principle, reference is made to the preceding embodiment.

In the following, with reference to FIG. 4 , a third embodiment of the invention is described. In contrast to the preceding embodiment, the abrasive 4 comprises an abrasive body 18 formed of abrasive grains 11 bonded with synthetic resin 19. The abrasive body 18 thus forms a first grinding layer 9 on the first side S₁ due to its surface, and forms a second grinding layer 17 on the second side S₂ due to its surface. With regard to the further construction and the further operational principle, reference is made to the preceding embodiments.

Hereinafter, with reference to FIG. 5 , a fourth embodiment of the invention is described. In contrast to the preceding embodiments, the abrasive 4 does not have a connecting element and the abrasive holder 3 does not have an associated counter-connecting element. The abrasive holder 3 comprises a first holder component 20 and a second holder component 21. The first holder component 20 is connected to the drive shaft 2 by means of the threaded connection 6. The first holder component 20 has a threaded bore 22, which is arranged concentrically to the axis of rotation 5. An associated threaded pin 23, which is part of the second holder component 21, can be screwed into the threaded bore 22. For passing the threaded pin 23 therethrough, the abrasive 4 comprises a central opening 24. The abrasive 4 is clamped between the holder components 20, 21 by screwing the threaded pin 23 into the threaded bore 22. For this purpose, the first holder component 20 forms a first annular region K₁ having a diameter D₁. On the other hand, the second holder component 21 forms an annular region K₂ having a diameter D₂. The following applies: 0.1·D≤D₁≤0.5·D. Furthermore, it applies that: 0.1·D≤D₂≤1.1·D, in particular 0.2·D≤D₂≤1·D, in particular 0.3·D≤D₂≤0.5·D. The smaller D₁, the larger the working region A. The larger D₂, the better the abrasive 4 is supported on the second side S₂ when a processor, exerting a tensile force F, is processing the workpiece W. For example, the following applies: D₁=D₂. With regard to the further construction and the further operational principle, reference is made to the preceding embodiments.

In general:

The drive shaft 2 may be formed integrally with the abrasive holder 3 or with the first holder component 20 of the abrasive holder 3. The shape and design of the grinding layer 9 and/or the grinding layer 17 can be combined in any desired way with a connecting element 13 and an associated counter-connecting element 7 of the abrasive holder 3 or with an abrasive holder 3 comprising a plurality of holder components 20, 21.

The supporting body 8 may be configured to be rigid and/or elastically deformable. Furthermore, the second holder component 21 may be configured to be rigid and/or elastically deformable. If the second holder component 21 is rigid, the abrasive 4 may also be configured to be flexible or bendable, for example as an abrasive on a backing. 

1. An abrasive for the production of a grinding tool comprising a grinding layer (9) for grinding a workpiece (W), and a connecting element (13) for connecting to an abrasive holder (3), characterized in that the grinding layer (9) and the connecting element (13) are arranged on a common side (S₁) for grinding while exerting a tensile force (F).
 2. An abrasive according to claim 1, characterized by a supporting body (8) on which the grinding layer (9) and the connecting element (13) are arranged.
 3. An abrasive according to claim 1 or 2, characterized in that the grinding layer (9) is attached directly to a supporting body (8) by means of an adhesive (10).
 4. An abrasive according to at least one of the preceding claims, characterized in that the grinding layer (9) is configured to be curved.
 5. An abrasive according to at least one of the preceding claims, characterized by a second grinding layer (17) which is arranged on the supporting body (8) and is opposite the first grinding layer (9).
 6. An abrasive according to at least one of the preceding claims, characterized in that the grinding layer (9) comprises abrasive grains (11).
 7. An abrasive according to at least one of the preceding claims, characterized in that the connecting element (13) is designed as a rotary connecting element.
 8. A grinding tool comprising a drive shaft (2) for driving the grinding tool (1) in rotation, an abrasive holder (3) arranged on the drive shaft (2), and an abrasive (4) replaceably arranged on the abrasive holder (3), with a grinding layer (9), characterized in that the grinding layer (9) faces the drive shaft (2) for grinding while exerting a tensile force (F).
 9. A grinding tool according to claim 8, characterized in that the abrasive (4) comprises a connecting element (13) for connecting to the abrasive holder (3).
 10. A grinding tool according to claim 9, characterized in that the abrasive holder (3) comprises a counter-connecting element (7) for connecting to the connecting element (13).
 11. A grinding tool according to at least one of claims 8 to 10, characterized in that the abrasive (4) comprises a supporting body (8) on which the grinding layer (9) and/or a connecting element (13) are arranged.
 12. A grinding tool according to at least one of claims 8 to 11, characterized in that the abrasive holder (3) for supporting the abrasive (4) is arranged at least partially on a side (S₂) of the abrasive (4) facing away from the drive shaft (2).
 13. A grinding tool according to at least one of claims 8 to 12, characterized in that the abrasive holder (3) comprises a first holder component (20) and a second holder component (21), between which the abrasive (4) is arranged.
 14. A method for operating a grinding tool comprising the steps of: providing a grinding tool (1) according to at least one of claims 8 to 13, and grinding a workpiece (W) by means of the grinding layer (9) while exerting a tensile force (F). 